Hello,
I have a QTR 8RC for a line sensing robot from Pololu. Right now all the sensor outputs ins are connected to MSP 432 GPIO input pins and a power of 3.3V is applied to the Vcc terminal. However, ALL my sensor readings are 00000000.
Would you please tell me what the issue could be and how to fix it?
Chi
Hello, Chi.
Can you post pictures showing your setup and how you have everything connected, including close-up pictures of the QTR-8RC board? How are you reading the sensor array? Can you post your full code?
- Amanda
I am having difficulty uploading the image from my phone (error msg says: File too large).
I will try again at a computer.
I have all 8 sensor pins plugged in using jumper wires. And the VCC plugged to 3.3v on msp432 and ground plugged to ground.
My code checks if the sensor readings are high or low and gives instructions to the mcu to adjust the pwms accordingly to keep the robot following the line.
However, upon noticing the sensors were not reading, I decided to test each of the pins with a multimeter. And they all output 0V on both white and back.
What could be the issue? Is there a calibration required? Do I need to connect the LEDs?
Please let me know what I need to do.
Thank you.
void gpio_config()
{
//Switches
MAP_GPIO_setAsInputPinWithPullUpResistor(GPIO_PORT_P1, GPIO_PIN1); // S1
MAP_GPIO_setAsInputPinWithPullUpResistor(GPIO_PORT_P1, GPIO_PIN4); // S2
//Set Output Pins for Motor Driver
MAP_GPIO_setAsOutputPin(GPIO_PORT_P6,GPIO_PIN6); // Output to H-Bridge - P6.6 / IN1
MAP_GPIO_setAsOutputPin(GPIO_PORT_P2,GPIO_PIN5); // Output to H-Bridge - P2.5 / IN2
MAP_GPIO_setAsOutputPin(GPIO_PORT_P2,GPIO_PIN6); // Output to H-Bridge - P2.6 / IN3
MAP_GPIO_setAsOutputPin(GPIO_PORT_P2,GPIO_PIN7); // Output to H-Bridge - P2.7 / IN4
MAP_GPIO_setOutputHighOnPin(GPIO_PORT_P2, GPIO_PIN5); // LEFT MOTOR
MAP_GPIO_setOutputLowOnPin(GPIO_PORT_P6, GPIO_PIN6);
MAP_GPIO_setOutputHighOnPin(GPIO_PORT_P2, GPIO_PIN7); // RIGHT MOTOR
MAP_GPIO_setOutputLowOnPin(GPIO_PORT_P2, GPIO_PIN6);
//Sensor Input PIns
MAP_GPIO_setAsInputPin(GPIO_PORT_P5, GPIO_PIN0); //P5.0 - L
MAP_GPIO_setAsInputPin(GPIO_PORT_P5, GPIO_PIN2); //P5.2
MAP_GPIO_setAsInputPin(GPIO_PORT_P3, GPIO_PIN6); //P3.6
MAP_GPIO_setAsInputPin(GPIO_PORT_P6, GPIO_PIN7); //P6.7 - C
MAP_GPIO_setAsInputPin(GPIO_PORT_P2, GPIO_PIN3); //P2.3 - C
MAP_GPIO_setAsInputPin(GPIO_PORT_P5, GPIO_PIN1); //P5.1
MAP_GPIO_setAsInputPin(GPIO_PORT_P3, GPIO_PIN5); //P3.5
MAP_GPIO_setAsInputPin(GPIO_PORT_P3, GPIO_PIN7); //P3.7 - R / Blue
//Encoder Pins
MAP_GPIO_setAsPeripheralModuleFunctionInputPin(GPIO_PORT_P4, GPIO_PIN1, GPIO_PRIMARY_MODULE_FUNCTION); //Output A1
MAP_GPIO_setAsPeripheralModuleFunctionInputPin(GPIO_PORT_P4, GPIO_PIN6, GPIO_PRIMARY_MODULE_FUNCTION); //Output B1
MAP_GPIO_setAsPeripheralModuleFunctionInputPin(GPIO_PORT_P3, GPIO_PIN0, GPIO_PRIMARY_MODULE_FUNCTION); //Output A2
MAP_GPIO_setAsPeripheralModuleFunctionInputPin(GPIO_PORT_P5, GPIO_PIN7, GPIO_PRIMARY_MODULE_FUNCTION); //Output B2
}
void clock_config()
{
//Set Clock
unsigned int dcoFrequency = 3E+6;
MAP_CS_setDCOFrequency(dcoFrequency); // Set DCO clock source frequency
MAP_CS_initClockSignal(CS_SMCLK, CS_DCOCLK_SELECT, CS_CLOCK_DIVIDER_1); // Tie SMCLK to DCO
MAP_Timer_A_configureUpMode(TIMER_A0_BASE,&upConfig_0); // Configure Timer A using above struct
MAP_Interrupt_enableInterrupt(INT_TA0_0); // Enable Timer A interrupt
}
/*
void UART_config()
{
// UART configuration
MAP_GPIO_setAsPeripheralModuleFunctionInputPin(GPIO_PORT_P1, GPIO_PIN2 | GPIO_PIN3, GPIO_PRIMARY_MODULE_FUNCTION);
MAP_UART_initModule(EUSCI_A0_BASE, &uartConfig);
MAP_UART_enableModule(EUSCI_A0_BASE);
MAP_UART_clearInterruptFlag (EUSCI_A0_BASE, EUSCI_A_UART_RECEIVE_INTERRUPT);
MAP_UART_enableInterrupt(EUSCI_A0_BASE, EUSCI_A_UART_RECEIVE_INTERRUPT);
MAP_Interrupt_enableInterrupt(INT_EUSCIA0);
MAP_Interrupt_enableSleepOnIsrExit();
MAP_Interrupt_enableMaster();
}
*/
void main(void)
{
// Stop watchdog timer
WDTCTL = WDTPW | WDTHOLD;
//UART_config();
clock_config();
led_config();
pwm_config();
gpio_config();
// Set Timer A period (PWM signal period)
TA2CCR0 = 16000 ;
TA0CCR0 = 16000 ;
// TA0CCR1 = 8000; //Left Motor full speed - 50% Duty Cycle
// TA2CCR1 = 8000; //Right Motor full speed
/*
// Set Duty cycle to 0 for calibration
TA2CCR1 = 0 ;
TA0CCR1 = 0 ;
// Set output mode to Reset/Set
TA2CCTL1 = OUTMOD_7 ;
TA0CCTL1 = OUTMOD_7 ;
// Initialize Timer A
TA2CTL = TASSEL__SMCLK | MC__UP | TACLR ;
TA0CTL = TASSEL__SMCLK | MC__UP | TACLR ;
// Initializing TimerA
MAP_Timer_A_configureUpMode(TIMER_A0_BASE, &upConfig_0);
MAP_Interrupt_enableInterrupt(INT_TA0_0);
*/
//start timer
MAP_Timer_A_startCounter(TIMER_A0_BASE, TIMER_A_UP_MODE);
while (1)
{
for(i=0; i<=5000; i++){}; //Calibrate Sensors
if(GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P6, GPIO_PIN7) && GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P2, GPIO_PIN3)){
//00011000
goStraight = 1;
s6 = 1;
w6 = 0;
}
else {s6 = 0;}
if(GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P5, GPIO_PIN0)) {
//10000000
goStraight = 0;
s2 = 1;
w2 = -80;
pastLine1 = 1;
pastLine2 = 0;
}
else {s2 = 0; w2 = 0;}
if(GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P5, GPIO_PIN0) && GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P5, GPIO_PIN2)){
//11000000
goStraight = 0;
s3 = 1;
w3 = -60;
}
else {s3 = 0; w3 = 0;}
if(GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P5, GPIO_PIN2) && GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P3, GPIO_PIN6)){
//01100000
goStraight = 0;
s4 = 1;
w4 = -40;
}
else {s4 = 0; w4 = 0;}
if(GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P3, GPIO_PIN6) && GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P6, GPIO_PIN7)){
//00110000
goStraight = 0;
s5 = 1;
w5 = -20;
}
else {s5 = 0; w5 = 0;}
if(GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P2, GPIO_PIN3) && GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P5, GPIO_PIN1)){
//00001100
goStraight = 0;
s7 = 1;
w7 = 20;
}
else {s7 = 0; w7 = 0;}
if(GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P5, GPIO_PIN1) && GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P3, GPIO_PIN5)){
//00000110
goStraight = 0;
s8 = 1;
w8 = 40;
}
else {s8 = 0; w8 = 0;}
if(GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P3, GPIO_PIN5) && GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P3, GPIO_PIN7)){
//00000011
goStraight = 0;
s9 = 1;
w9 = 60;
}
else {s9 = 0; w9 = 0;}
if(GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P3, GPIO_PIN7)){
//00000001
goStraight = 0;
s10 = 1;
w10 = 80;
pastLine1 = 0;
pastLine2 = 1;
}
else {s10 = 0; w10 = 0;}
if(GPIO_INPUT_PIN_LOW == MAP_GPIO_getInputPinValue(GPIO_PORT_P3, GPIO_PIN7) && GPIO_INPUT_PIN_LOW == MAP_GPIO_getInputPinValue(GPIO_PORT_P3, GPIO_PIN5) && GPIO_INPUT_PIN_LOW == MAP_GPIO_getInputPinValue(GPIO_PORT_P5, GPIO_PIN1) && GPIO_INPUT_PIN_LOW == MAP_GPIO_getInputPinValue(GPIO_PORT_P2, GPIO_PIN3) && GPIO_INPUT_PIN_LOW == MAP_GPIO_getInputPinValue(GPIO_PORT_P6, GPIO_PIN7) && GPIO_INPUT_PIN_LOW == MAP_GPIO_getInputPinValue(GPIO_PORT_P3, GPIO_PIN6) && GPIO_INPUT_PIN_LOW == MAP_GPIO_getInputPinValue(GPIO_PORT_P5, GPIO_PIN2) && GPIO_INPUT_PIN_LOW == MAP_GPIO_getInputPinValue(GPIO_PORT_P5, GPIO_PIN0) && pastLine1 == 1){
//00000000 -->1 Line on far right
goStraight = 0;
s11 = 1;
w11 = 100;
}
else {s11 = 0; w11 = 0;}
if(GPIO_INPUT_PIN_LOW == MAP_GPIO_getInputPinValue(GPIO_PORT_P3, GPIO_PIN7) && GPIO_INPUT_PIN_LOW == MAP_GPIO_getInputPinValue(GPIO_PORT_P3, GPIO_PIN5) && GPIO_INPUT_PIN_LOW == MAP_GPIO_getInputPinValue(GPIO_PORT_P5, GPIO_PIN1) && GPIO_INPUT_PIN_LOW == MAP_GPIO_getInputPinValue(GPIO_PORT_P2, GPIO_PIN3) && GPIO_INPUT_PIN_LOW == MAP_GPIO_getInputPinValue(GPIO_PORT_P6, GPIO_PIN7) && GPIO_INPUT_PIN_LOW == MAP_GPIO_getInputPinValue(GPIO_PORT_P3, GPIO_PIN6) && GPIO_INPUT_PIN_LOW == MAP_GPIO_getInputPinValue(GPIO_PORT_P5, GPIO_PIN2) && GPIO_INPUT_PIN_LOW == MAP_GPIO_getInputPinValue(GPIO_PORT_P5, GPIO_PIN0) && pastLine2 == 1){
//1 <-- 00000000 Line on far left
goStraight = 0;
s1 = 1;
w1 = -100;
}
else {s1 = 0; w1 = 0;}
//PID
if(GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P6, GPIO_PIN7) && GPIO_INPUT_PIN_HIGH == MAP_GPIO_getInputPinValue(GPIO_PORT_P2, GPIO_PIN3)){
iErr = iErr + err;
}
else{iErr = 0;}
//CONTROL COMPUTATION
totalSensors = s1 + s2 + s3 + s4 + s5 + s6 + s7 + s8 + s9 + s10 + s11;
sumRead = w1 + w2 + w3 + w4 + w5 + w6 + w7 + w8 + w9 + w10 + w11;
//AVERAGE OF READINGS
err = center - (sumRead/totalSensors);
if(err < 0){
goRight =1;
}else if(err>0){
goRight =0;
}
dErr = err - lastErr;
lastErr = err;
control = kp * err + kd * lastErr + ki * iErr;
if(goStraight == 0)
{
if(goRight == 1)
{
TA0CCR1 = control*-1; //Left Motor speed up relative to the error amount
TA2CCR1 = 0;
}
else if(goRight == 0){
TA0CCR1 = 0;
TA2CCR1 = control; //Right Motor speed up relative to the error amount
}
}
else if(goStraight == 1){
TA0CCR1 = 1500; //Left Motor full speed - 50% Duty Cycle
TA2CCR1 = 1500; //Right Motor full speed
}
}
}
The QTR-xRC sensors do not just output a digital high or low signal. The digital I/O lines controlling each sensor on the sensor array must be driven high to charge the on-board circuit and then set as an input so that the I/O line can measure the discharge time. You can find more information on how the sensors work in the QTR-xRC section of the QTR Reflectance Sensor Application Note.
- Amanda
Thank you for responding Amanda. The images still are refusing to upload on the website, even after compressing them.
I have the sensors and microcontroller connected to a common ground and the 8 pins connected to digital input output.
Would programming it in this format perform the task you have described?
MAP_GPIO_setAsOutputPin
MAP_GPIO_setOutputHighOnPin
MAP_GPIO_setAsInputPin
You need to add a minimum delay to charge the line(s) and measure the time it takes for the line(s) to go low. As I said in my previous post, you can find explicit details on how the sensors work, including instructions to properly read them, in the QTR reflectance sensor application note. For reference, you could look at the source code of readPrivate() in the QTRSensorsRC class of our Arduino library for the Pololu QTR Reflectance Sensors.
- Amanda
Thank you.